I. Field of the Invention
The invention relates to strapping apparatus for applying a thermal plastic strap about an object, and, more particularly, the invention relates to a strapping apparatus for applying a thermoplastic strap about an object which includes a clamp to hold the object against a platen while the platen is rotated to wind the strap about the object.
II. Description of the Prior Art
Strapping machines for wrapping plastic strips about objects are known in the prior art, for example, U.S. Pat. No. 3,636,861 issued to Weller on Jan. 25, 1971 and entitled "Strapping Machine". The Weller patent shows a machine which feeds a plastic strap about the object. While the plastic strap is being fitted about the object, a seal is positioned adjacent the strap. Once the leading end of the strap is about the object, tension is applied on the strap and the seal is applied to the plastic strap. The seal being a metallic plate which is about the overlapping portion of the strap and crimped thereto. The strap is then severed so that the portion toward the supply is free from the portion of the strap which is wound about the object. The machine is then prepared to apply a strap about another object.
Another patent, U.S. Pat. No. 3,489,076 issued to Countrymen on Jan. 13, 1970 and entitled "Automatic Strapping Apparatus", shows an apparatus which applies a strap about a number of articles which are compressed into a single bundle (or object). The strap is run out from a supply about the articles and is crimped along the overlapping portion of the strap by a clamp. Tension is applied on the strap and on the articles to compress them. The clamp remains on the strap even after the portion of the strap wound about the articles is severed from the supply.
The patents mentioned above are examples of the types of strapping machines known in the prior art. It is also known to utilize heated wires to sever thermoplastic materials as shown in U.S. Pat. No. 3,754,489 issued to Carver on Aug. 28, 1973 and entitled "Smokeless Cut-off Blade For Plastic Wrapping Film". In Carver a plastic film is wound about an article, for example, food placed within a tray to be wrapped with the plastic film and placed within a display. The film is then severed by passing the portion of the film toward the supply across a heated knife. In U.S. Pat. No. 3,064,111 issued to Newman on Nov. 13, 1962 and entitled "Plastic Cutting Device" utilizes heated wires to cut thermoplastic material. Newman is of interest because it shows apparatus for cutting thermoplastic. The wires have a high electrical resistance and when a current is passed there through, heat is generated within the wire which then in turn is transmitted to the thermoplastic material. The wire is drawn through the plastic material as the plastic material moves along and an electrical current is applied to the wire. Thus the thermoplastic material is heated in order to soften the material and then sawed through by the thin wire.
None of the prior construction shows a strapping apparatus which has a platen to receive the object and a clamp for clamping the object to the platen with one end of the strap to be wrapped about the object placed between the object and the platen, and which rotates the platen to wrap the strap about the object.